The invention may relate generally to a precast concrete lift anchor assembly for precast Portland cement concrete shapes. In another aspect, the invention may relate to a recess insert for forming a cavity in Portland cement concrete. In another aspect, the invention may relate to a concrete lift anchor partially embeddable in Portland cement concrete, joined with a pair of complementary recess insert parts for forming a cavity in Portland cement concrete, to enable access to an unembedded portion of the lift anchor for coupling with a lifting apparatus.
It is known to utilize precast Portland cement concrete shapes for installation on a construction project. Such shapes may be very heavy, which may necessitate the use of specialized equipment, such as cranes, helicopters, cables, chains, hooks, clutches, and the like, for safe lifting, moving, and installation.
Concrete shapes may be cast with integral metal lift anchors, to which hooks, cables, chains, and the like, may be attached for facilitating the handling of the concrete shapes. Such metal lift anchors may be heavy, large, and unwieldy. Their configuration may complicate the placement of reinforcing steel and prestressing strands, contributing to increased time and costs, and potentially increasing the risk of reinforcement and pre-stressing selection and installations failing to meet established or required standards. This may be due, in part, to preoccupation by a construction contractor or engineer with optimizing the balance between the load capacity of a lift anchor, and its cost and utility.
The lift anchor may be located within the concrete shape adjacent known prestressing strands. Factors such as the dimensions of the concrete shape, the designed location for the lift anchor within the concrete shape, the required number of lift anchors, the required number of prestressing strands, and the like, may control the spatial relationship of the lift anchor and the prestressing strands. This may result in undesirable crowding of the lift anchor and the prestressing strands. It may be necessary to reconfigure the lift anchor and/or prestressing strands due to concrete dimensions, such as insufficient concrete cover adjacent the lift anchor, prestressing strands, and/or other reinforcement. Reconfiguration may be complicated with prior art lift anchors, for example those that are fabricated as single piece, that incorporate lower strength materials or configurations, or that require additional components, such as ties, for attaching the lift anchor to prestressing strands and/or other reinforcement.
The lift anchor may be coupled with a recess insert configured to isolate the exposed portion from the adjacent concrete. As fresh concrete is placed, the recess insert may prevent contact of the concrete with the exposed portion of the lift anchor. When the concrete has cured, the recess insert may be disassembled, leaving the lift anchor partly embedded in the concrete, and partly exposed for connecting hooks, cables, chains, and other lifting and transporting equipment. Selection of a recess insert and lift anchor, and the number and location of lift anchors, may be finalized relatively early in the design phase. Last-minute modifications to or substitution for a pre-selected lift anchor may be complicated, untimely, and costly.
A lift anchor and recess insert that has a high strength-to-size ratio, is compact, can readily accommodate different loading configurations, and comprises a relatively straightforward manufacture, is desirable.